Fix for frequency in multi-study view

[eugeniomazzone]

Fix #10967

Describe changes proposed in this pull request:

• Function AlterationCountServiceUtil.setupAlterationGeneCountsMap now initialize the profiledCases to 0.
• Added an additional piece of code (after above function is called) in AlterationCountServiceImpl to update the number of profiled samples with the correct one, for each study and each gene.

After the fix, the frequency displayed on the multi-study view appear to be correct as it's 23.8% as expected instead of 100%.

Before fix:

After fix:

[zeynepkaragoz]

@inodb Eugenio worked on fixing one of the open issues, could you point us to some potential reviewers please?

[inodb]

@haynescd @alisman this is a fix in legacy code for determining alteration frequency in multi-study query. Thoughts?